In the prior art, the automobile has airbag to improve the safety performance of the vehicle. The airbag for the position of the driver is installed in the steering mechanism. When the automobile is subjected to a serious front collision or a quasi front collision (equal to a frontal collision on a rigid wall at a speed of faster than I6 km/h), the collision-detection and ignition device in the automobile will transfer a sudden-deceleration signal to the detonation device of the gas generator, so as to generate nitrogen with related substances, and the airbag in front of the driver is inflated. Helium will fill the airbag in a period of less than 0.05 s, and the main matter for generating gas is sodium azide NaN3. According to the calculation, after explosion, 100 g of NaN3 can generate about 50 L of nitrogen, which fully filled in the airbag. The airbag, at one side thereof, is provided with exhaust holes, when the driver contacts and presses the inflated airbag, the nitrogen in the airbag is discharged through the exhaust holes, and the hot nitrogen will be cooled quickly after being discharged. In this way, the energy of the forward movement of the driver is absorbed. However, when the collision occurs, the airbag will deploy or be ejected at a very fast speed, and the steering wheel is fixed, so that the driver's head contacts with the airbag in a relatively short travel. Due to the short buffer process, the airbag will impact on the driver's head severely in a short buffer travel, and it is easy for the head of the driver to be injured.
In order to solve the above problems, the invention makes some improvements.